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Prospective Improvements of IVS Products and Evolvement of Observing Programs
Harald Schuh WG2 Chair
Vienna University of Technology
Wolfgang SchlüterIVS Chair
Bundesamt für Kartographie und Geodäsie Fundamentalstation Wettzell
Nancy VandenbergIVSCC Director
NASA Goddard Space Flight Center
I V S - International VLBI Service for Geodesy and Astrometry
IVS is a service of IAG - International Association of Geodesy IAU - International Astronomical Union FAGS - Federation of Astronomical and Geophysical Data Analysis Services
Main tasks of the IVS Maintenance of the ICRF (International Celestial Reference Frame)
radio source positions and changes Provision of products for
ITRF (International Terrestrial Reference Frame)• station positions and velocities
EOP - Earth Orientation Parameters• monitoring the celestial pole (d, dψ)• monitoring Universal Time (UT1) and length of day (LOD) • monitoring polar Motion (xp, yp)
The IVS 1999 - 2001 IVS inauguration was on 1st of March, 1999 Demand for continuity in maintaining the reference
frames forced to employ and accept the existing infrastructure existing observing programs (NEOS, CORE, ....) related data handling
IVS efforts in 1999 - 2001 installation of its structure and components Get used to the new tasks
2001 review of products and observing programs ==> WG2 Basis for improving products and evolving observing programs
to meet service requirements
WG2 onProduct Specification and Observing Programs
WG 2 established at the 5th IVS DB-Meeting on February 15th, 2001
The assignment of WG2 was to review the usefulness and appropriateness of current IVS products, recommend guidelines for accuracy, timeliness, and redundancy, review the quality and appropriateness of observing programs, set goals for improvements of IVS products, suggest how these may possibly be achieved in the future, suggest a realistic set of observing programs, taking into account existing agency
programs.
Complete report was presented in November 2001 and accepted by the IVS Directing Board on Feb. 14th, 2002
available: http://ivscc.gsfc.nasa.gov
within IVS Annual Report 2001
Members of the WG2
Harald Schuh (chair), TU Vienna (A) Patrick Charlot, Obs. Bordeaux (F) Hayo Hase, BKG (D) Ed Himwich, NASA/GSFC (USA) Kerry Kingham, USNO (USA) Calvin Klatt, EMR (Canada) Chopo Ma, NASA/GSFC (USA)
Zinovy Malkin, IAA (RU) Arthur Niell, MIT Haystack (USA) Axel Nothnagel, Univ. Bonn (D) Wolfgang Schlüter, BKG (D) Kazuhiro Takashima, GSI (JP) Nancy Vandenberg, NASA/GSFC
(USA)
Experts in various fields of VLBI Involving many agencies Different nations
to obtain broad acceptance within IVS
Rationale and motivation for the work of WG2
Fundamental role of VLBI for the realization and maintenance of global reference frames
unique for the ICRF, essential for EOPs and scale of the ITRF
Requirement for precise reference frames (10-9), consistent for decades: IGGOS - Integrated Global Geodetic Observing System
Demand for combination of all techniques to achieve the required accuracy to eliminate systematic errors to generate reliable and redundant results
Collaboration of all IAG Services (IVS, ILRS, IGS, IDS, ... IERS)
IVS products (some examples from WG2 Report)
Products Status Goals(2002-2005) polar motion accuracy xp ~100 s, yp ~200 s xp, yp: 50 ... 25 s
latency 1-4 weeks... 4 months 4 - 3 days...1day resolution 1 day 1 day...1h... 10min freq. of sessions ~3 d/week
.........7d/week UT1 accuracy 5... 20 s 3.................. 2 s
latency 1 week 4 - 3 days .... 1day resolution 1 day1 day ....... 10min
, accuracy 100... 400 arcsec 50...25 arcsec latency 1-4 weeks... 4 months 4 - 3days... 1 day resolution 1 day
1 day freq. of sessions ~3 d/week .......... 7 d/week TRF (x,x,z) accuracy 5-20 mm 5 .............. 2 mm ....
.... .... CRF accuracy 0.25-3 mas 0.25 mas (improved
distribution) freq. of solution 1 y1 y latency 3-6 months 3 ............. 1 month(s)
...... ....... ....... .......
More IVS products (see WG2 Report) EOP - dUT1/dt (lod)
- dxp/dt, dyp/dt TRF - x,y,z time series
- episodic events- annual solutions- non-linear changes
CRF - source structure- flux density
Geodynamical Parameters - solid Earth tides h, l- ocean loading A, - atmospheric loading α
Physical Parameters - tropospheric parameters (zenith delays, gradients)- ionospheric mapping- light deflection parameter
New IVS observing programs IVS Program Committee was established in Sept. 2001 appropriate observing programs started 2002 for
Earth Orientation Parameters (EOP): IVS-R1 ... IVS-R4, IVS-INT1 Two rapid turn-around sessions each week, Comparable xp, yp results. Additional sessions employing S2 and K4 techniques (IVS-E3, IVS-INT2)
Terrestrial Reference Frame (TRF): IVS-T2 Monthly TRF sessions with 8 stations
Celestial Reference Frame (CRF): IVS-CRF Bi-monthly RDV sessions using the VLBA and 10 geodetic stations,
CONT, annually or semi-annually IVS-CONT02 14-day continuous sessions to demonstrate the best results that VLBI can offer in 2002: CONT-session, October 16-31, 2002
Monthly R&D sessions: IVS-R&D to investigate instrumental effects, research the network offset problem
Observing program 2002: geodetic VLBI observations will be increased by about 30% Goal: future increase by ~100% till 2005
Improvements required
weekend gaps, automation for unattended observing needed
reduce time delay and reduce expenses development of a modern disc based recording system (Mk5) development of data transfer via the Internet (e-VLBI)
global network configuration has to be improved especially in the southern hemisphere encourage additional institutions and include the S2 and K4 technologies more observing time is required overall
timeliness, shorten turn-around time at the correlators (better logistical organization of tape/disc transport)
robustness of the products, more analysis centers with different software
Finally ....
To meet the ambitious goals all responsible members of the contributing agencies are kindly asked to support the IVS as much as possible
Thank you
